1. Field of the Invention
The present invention relates to a method for the manufacture of block polyester polyols, especially polyester polyols in which tetrahydric alcohols are not used in the manufacturing process and ethylene glycol is preferably not used in the manufacturing process, and to polyurethanes obtained from such block polyester polyols. In particular, the invention relates to a method for the manufacture of polyester polyols from aliphatic polycarboxylic acids and polyhydric alcohols in which the acids and alcohols are of similar molecular weight, and especially a method in which the block polyester polyols are formed by reaction of a dicarboxylic acid with a mixture of secondary dihydric alcohols and primary trihydric alcohols, and they by reaction of the resultant product with additional primary trihydric alcohol.
2. Description of the Prior Art
Methods are known for the manufacture of polyester polyols by reacting polycarboxylic acids, or esters or anhydrides thereof, with polyhydric alcohols in the presence of catalysts. Typical reaction times are stated to vary in the range of from 12 to 16 hours at temperatures of 130.degree. to 240.degree. C. A wide variety of carboxylic acids and polyhydric alcohols may be used, as is discussed in U.S. Pat. Nos. 4,525,574 and 4,716,213, both of G. N. Altounian, which issued June 25, 1985 and Dec. 29, 1987, respectively.
The manufacture of polyester polyols from a mixture of 73.1 parts of adipic acid, 54.8 parts of a diol mixture of 21% by weight of 1,4-butanediol, 52% by weight of 1,5-phentanediol and 27% by weight of 1,6-hexanediol, and 2.95 parts of trimethylol propane by esterification at normal pressure and at temperatures of up to 210.degree. C., is disclosed in Example 1 of U.S. Pat. No. 4,362,825 of H. Grabhoefer et al, which issued Dec. 07, 1982. The patent is directed to the manufacture of polyisocyanates from liquid polyester polyols having hydroxyl numbers of 40 to 80 and molecular weights of 1500 to 5000.
Polyesters that have hydroxyl groups and include reaction products of polyhydric, preferably dihydric and optionally trihydric alcohols, with polyvalent, preferably divalent, carboxylic acids are disclosed in U.S. Pat. No. 4,608,413 of K. Nachtkamp et al, which issued Aug. 26, 1986. The polyesters are used in stoving lacquers.
A polyester polyol having an acid number of about 7 and formed from 1248 g of neopentyl glycol, 295 g of trimethylol propane and 2331 g of azelaic acid (1,7-heptanedicarboxylic acid i.e. 1,9-nonanedioic acid ) is disclosed in Example 5 of U.S. Pat. No. 4,255,541 of J. A. Simms, which issued Mar. 10, 1981.
R. H. Blanpied discloses in U.S. Pat. No. 4,400,477, which issued Aug. 23, 1983, that polyester polyols formed from mixtures of aliphatic and aromatic carboxylic acids had superior miscibility with fluorotrichloromethane than did polyester polyols formed from only aliphatic carboxylic acids.
U.S. Pat. No. 3,888,908 of J. M. Cross, which issued June 10, 1975, discloses polyester glycols formed from dicarboxylic acids, dicarboxylic acid anhydrides, dihydric alcohols and trihydric alcohols. The anhydrides are exemplified by phthalic acid anhydride and isophthalic acid anhydride.
Published Japanese patent application No. 61-026612 of Kuraray KK, published Feb. 5, 1986, discloses mixed polyols formed from 3-methyl-1,5-pentanediol, polypropylene glycol and adipic or azelaic acid, and chain extended with ethylene glycol or butanediol.
Canadian Patent No. 1 129 598 of W. Jarre et al, which issued Aug. 10, 1982, discloses polyester polyols manufactured from dicarboxylic acids, preferably aliphatic acids having 2 to 12 carbon atoms, and di- and multifunctional alcohols, preferably ethylene glycol and diethylene glycol. It is also disclosed that alkanolamines e.g. triethanolamine and triisopropanolamine, may be used as multifunctional alcohols.
Polyester polyols derived from butane-1,3-diol, at least one aliphatic polyhydroxy compound containing four hydroxy groups e.g. pentaerythritol, and adipic and/or glutaric acid is disclosed in U.K. patent specification No. 882 603 of Imperial Chemical Industries Limited, published Nov. 15, 1961.
A process for the manufacture of a polyester polyol is described in GB No. 2 021 602A of A. G. Corry, published Dec. 05, 1979. The process comprises reacting an organic polyol with a lower alkyl ester of a polycarboxylic acid and removing lower alkanol from the reaction mixture as it is formed and, towards the end of the reaction, adding an organic polyol or a polycarboxylic acid to the reaction mixture and then continuing the reaction. Other processes for the preparation of polyester polyols are described in Canadian Patent No. 1 059 529 of H. C. Vogt et al, which issued July 31, 1979.
A process for the preparation of block polyester polyols in the presence of N-phenyl dialkanolamines is disclosed in a U.S. Pat. No. 4,789,719 of G. N. Altounian, which issued Dec. 06, 1988.